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Railcom Decoder
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@Asbelos
Asbelos committed Sep 30, 2024
1 parent 0712eef commit 29e9b8c
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5 changes: 5 additions & 0 deletions IO_I2CRailcom.h
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Expand Up @@ -50,6 +50,7 @@
#include "I2CManager.h"
#include "DIAG.h"
#include "DCCWaveform.h"
#include "Railcom.h"

// Debug and diagnostic defines, enable too many will result in slowing the driver
#define DIAG_I2CRailcom
Expand All @@ -61,6 +62,7 @@ class I2CRailcom : public IODevice {
uint8_t _UART_CH=0x00;
byte _inbuf[65];
byte _outbuf[2];
Railcom _channelMonitors[2];
public:
// Constructor
I2CRailcom(VPIN firstVpin, int nPins, I2CAddress i2cAddress){
Expand Down Expand Up @@ -120,6 +122,9 @@ class I2CRailcom : public IODevice {
for (int i = 0; i < inlength; i++){
DIAG(F("[0x%x]: 0x%x"), i, _inbuf[i]);
}
auto locoid=_channelMonitors[_UART_CH].getChannel1Loco(_inbuf);
DIAG(F("Railcom Channel1=%d"), locoid);

#endif
}

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164 changes: 164 additions & 0 deletions Railcom.cpp
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/*
* SEE ADDITIONAL COPYRIGHT ATTRIBUTION BELOW
* © 2024 Chris Harlow
* All rights reserved.
*
* This file is part of DCC-EX
*
* This is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* It is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
*/

/** Sections of this code (the decode table constants)
* are taken from openmrn under the following copyright.
*
* Copyright (c) 2014, Balazs Racz
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
**/

#include "Railcom.h"
#include <FSH.h>

/** Table for 8-to-6 decoding of railcom data. This table can be indexed by the
* 8-bit value read from the railcom channel, and the return value will be
* either a 6-bit number, or one of the defined Railcom constrantrs. If the
* value is invalid, the INV constant is returned. */

// These values appear in the railcom_decode table to mean special symbols.
static constexpr uint8_t
// highest valid 6-bit value
MAX_VALID = 0x3F,
/// invalid value (not conforming to the 4bit weighting requirement)
INV = 0xff,
/// Railcom ACK; the decoder received the message ok. NOTE: There are
/// two codepoints that map to this.
ACK = 0xfe,
/// The decoder rejected the packet.
NACK = 0xfd,
/// The decoder is busy; send the packet again. This is typically
/// returned when a POM CV write is still pending; the caller must
/// re-try sending the packet later.
BUSY = 0xfc,

/// Reserved for future expansion.
RESVD1 = 0xfb,
/// Reserved for future expansion.
RESVD2 = 0xfa;

const uint8_t HIGHFLASH decode[256] =
// 0|8 1|9 2|a 3|b 4|c 5|d 6|e 7|f
{ INV, INV, INV, INV, INV, INV, INV, INV, // 0
INV, INV, INV, INV, INV, INV, INV, ACK, // 0
INV, INV, INV, INV, INV, INV, INV, 0x33, // 1
INV, INV, INV, 0x34, INV, 0x35, 0x36, INV, // 1
INV, INV, INV, INV, INV, INV, INV, 0x3A, // 2
INV, INV, INV, 0x3B, INV, 0x3C, 0x37, INV, // 2
INV, INV, INV, 0x3F, INV, 0x3D, 0x38, INV, // 3
INV, 0x3E, 0x39, INV, NACK, INV, INV, INV, // 3
INV, INV, INV, INV, INV, INV, INV, 0x24, // 4
INV, INV, INV, 0x23, INV, 0x22, 0x21, INV, // 4
INV, INV, INV, 0x1F, INV, 0x1E, 0x20, INV, // 5
INV, 0x1D, 0x1C, INV, 0x1B, INV, INV, INV, // 5
INV, INV, INV, 0x19, INV, 0x18, 0x1A, INV, // 6
INV, 0x17, 0x16, INV, 0x15, INV, INV, INV, // 6
INV, 0x25, 0x14, INV, 0x13, INV, INV, INV, // 7
0x32, INV, INV, INV, INV, INV, INV, INV, // 7
INV, INV, INV, INV, INV, INV, INV, RESVD2, // 8
INV, INV, INV, 0x0E, INV, 0x0D, 0x0C, INV, // 8
INV, INV, INV, 0x0A, INV, 0x09, 0x0B, INV, // 9
INV, 0x08, 0x07, INV, 0x06, INV, INV, INV, // 9
INV, INV, INV, 0x04, INV, 0x03, 0x05, INV, // a
INV, 0x02, 0x01, INV, 0x00, INV, INV, INV, // a
INV, 0x0F, 0x10, INV, 0x11, INV, INV, INV, // b
0x12, INV, INV, INV, INV, INV, INV, INV, // b
INV, INV, INV, RESVD1, INV, 0x2B, 0x30, INV, // c
INV, 0x2A, 0x2F, INV, 0x31, INV, INV, INV, // c
INV, 0x29, 0x2E, INV, 0x2D, INV, INV, INV, // d
0x2C, INV, INV, INV, INV, INV, INV, INV, // d
INV, BUSY, 0x28, INV, 0x27, INV, INV, INV, // e
0x26, INV, INV, INV, INV, INV, INV, INV, // e
ACK, INV, INV, INV, INV, INV, INV, INV, // f
INV, INV, INV, INV, INV, INV, INV, INV, // f
};
/// Packet identifiers from Mobile Decoders.
enum RailcomMobilePacketId
{
RMOB_POM = 0,
RMOB_ADRHIGH = 1,
RMOB_ADRLOW = 2,
RMOB_EXT = 3,
RMOB_DYN = 7,
RMOB_XPOM0 = 8,
RMOB_XPOM1 = 9,
RMOB_XPOM2 = 10,
RMOB_XPOM3 = 11,
RMOB_SUBID = 12,
RMOB_LOGON_ASSIGN_FEEDBACK = 13,
RMOB_LOGON_ENABLE_FEEDBACK = 15,
};


Railcom::Railcom() {
haveHigh=false;
haveLow=false;
}

int16_t Railcom::getChannel1Loco(uint8_t * inbound) {
auto v1=GETHIGHFLASH(decode,inbound[0]);
if (v1>MAX_VALID) return -1;
auto v2=GETHIGHFLASH(decode,inbound[1]);
if (v2>MAX_VALID) return -1;
auto packet=(v1<<6) | v2;
// packet is 12 bits TTTTDDDDDDDD
auto type=packet>>8;
auto data= packet & 0xFF;
if (type==RMOB_ADRHIGH) {
holdoverHigh=data;
haveHigh=true;
}
else if (type==RMOB_ADRLOW) {
holdoverLow=data;
haveLow=true;
}
else if (type==RMOB_EXT) {
/* ignore*/
}
else {
haveHigh=false;
haveLow=false;
}
if (haveHigh && haveLow) return ((holdoverHigh<<8)| holdoverLow);
return -1; // no loco info available
}
35 changes: 35 additions & 0 deletions Railcom.h
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/*
* © 2024 Chris Harlow
* All rights reserved.
*
* This file is part of DCC-EX
*
* This is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* It is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
*/

#ifndef Railcom_h
#define Railcom_h
#include "Arduino.h"

class Railcom {
public:
Railcom();
int16_t getChannel1Loco(uint8_t * inbound);

private:
uint8_t holdoverHigh,holdoverLow;
bool haveHigh,haveLow;
};

#endif

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